In recent years, with the employment of micromachine techniques and ultra microfabrication techniques, developed is a system in which conventional apparatus to conduct sample preparation, chemical analyses, chemosynthesis, etc. and means (for example, pumps, valves, flow passages, sensors, etc.) are miniaturized so as to be integrated into a single tip (for example, Patent Document 1). This system is also called μ-TAS (Micro Total Analysis System) with which a sample (for example, the urine of a person who undergoes an examination, saliva, extracted solution in which blood is subjected to DNA treatment, etc.) and reagents are mixed in a member called a microchip and the characteristic of the sample is examined by the detection of the reaction of the mixture.
In the microchip, groove fabrication is conducted for a substrate made of a resin material or glass material by a photolithographic process (a process producing grooves by etching a pattern image with chemicals) or the application of laser beams such that the substrate is provided with minute flow passage to allow regents and samples to flow and storage sections to storage reagents. Various patterns of minute flow passage and storage sections are proposed (for example, Patent Document 1).
At the time of investigating the characteristic of a sample by the use of these microchips, liquids such as reagents and samples stored in a microchip are fed to flow passages by micro pumps and the like so that reagents and samples are made to react in the flow passages and led to a detected section to detect the characteristic. In the detected section, object substances are detected by for example, an optical detecting method.
In the microchip, liquids in a slight amount are mixed with a predetermined mixture ratio in a minute flow passage, and then the liquids are made to perform reaction. In such a case, in order to administrate a mixture ratio of the both liquids with sufficient accuracy, the quantification of a liquid becomes very important. For such a request, generally, liquid is quantified by the use of a micropipette and the like and the quantified liquid component is injected into the microchip. However, with such a method, since there is fear of injection leakage, there is a problem that the injected amount is not accurate. In addition, there is a problem that since it is necessary to quantify a required reagent by only the required number of liquid components, the quantification becomes complicate.
For such problems, Patent Document 2 discloses a slight amount liquid controlling mechanism in which a liquid is drawn by a capillary action from a first flow passage to an inside of a third flow passage communicating between the first flow passage and a second flow passage, and then the liquid remaining the first flow passage is removed and liquid droplet with a volume corresponding to the volume of the third flow passage is prepared. Further, Patent Document 3 discloses a method with which a liquid in a chip is shifted with a centrifugal force caused by the rotation of the chip and the liquid is divided and quantified by the volume of a flow passage.